Food Planning - Salt

Food Planning - Salt

Salt mine at Maras, Peru

(Three Minute Read)

Our first training for Kokoda and our experience on that track in 2010 opened up our thinking to the utility of adding salt to our diets. We struggled training in the humidity of a Sydney summer and were left felling smashed at the end of each 16km training session, even though we had taken hydrolytes and plenty of water. Eventually we uncovered the benefit of adding salt tablets to our walks and for many of us the transformation they made was marked. Deep fatigue vanished, post walk recovery was more immediate and strength remained during the course of the day.

Was it just the salt? Anecdotal evidence across the group suggested as much, and ever since then any training in the heat has included salt tablets. Or should it? How do we manage our salt intake, especially if we are also trying to manage hypertension, which some of us regrettably do?

We have never settled on exactly how many tablets are needed, as we found the amount of salt taken varies from trekker to trekker. And we never really settled on when to take the salt. Before the day starts or as the day progresses? Many of us were inclined to the latter.  But ultimately our reservations about salt derived from our exposure to various health authorities and their messages to avoid excessive use of it in our daily diets so we are always left wondering how much is enough and how much is too much?

This short paper explores the general wisdom out there relating to salt (or rather sodium) in our trekking diets. It addresses our trekking diets only.  We are not disputing or advising against the collective published wisdom about salt in our every day diets. What we took to help out on Kokoda is not what we ingest as part of our daily diets, that’s for sure.

What is Salt?

We all remember from our high school chemistry that salt is ‘sodium chloride’. Does NaCL take you back? It’s a compound made up of an element of sodium and an element of chlorine. Sodium chloride melts at 1,474°F (801°C), boils at 2,670°F (1,465°C), has a density of 2.16 g/cm3 (at 25°C), and conducts electricity when dissolved or in the molten state.[1]  Some interesting facts there, but it’s the capacity of sodium to conduct electricity which is important to the human body and why we are interested in it rather than in the chlorine. It’s also of interest because sodium has a role to play in the regulation of body fluids.

Salt or Sodium?

Sodium is one component of salt and it’s important to note that they are not really interchangeable terms and, given it’s the sodium bit that we are mainly focused on lets’ stick with sodium since that is the most consistent reference point on our food labels. Indeed, most food labels may only state the sodium content. Don't confuse salt and sodium figures.

How does the Body Use Sodium?

Sodium is essential for proper nerve function, given our nervous system is actually an electrical system. But because we are talking about our nervous system we are talking about a range of other functions which salt impacts. At the risk of getting technical, “sensation, emotions, thought and movement all depend on voltage-gated sodium channels — transmembrane proteins that initiate action potentials in nerve, muscle and other electrically excitable cells.” [2]  Did you see that? Emotions. And movement. How we feel. Our capacity to think, our ability to exercise judgement, and our mobility are impacted by sodium. Or the lack of it. And that’s why we are interested in it as trekkers, especially trekkers walking in hot and humid conditions.  

Salt (NaCl) is ionic. Ionic. Not ironic.  When ionic compounds dissolve in water, they separate into positive and negative ions. These ions are in solution in our blood and in our cells. 

Salt separates into positive sodium (Na+) and negative chloride (Cl-) ions. Separated ions allow a solution to conduct an electric current. This is how the body sends nerve impulses. If you touch a hot stove, for example, nerve cells in your skin sense the heat. Sodium ions (Na+) in the fluid surrounding the nerve cells get pumped into the nerves. At the same time, potassium (K+) ions get pumped out of the nerves. This allows an impulse to be conducted through the nerves to the muscles of your arm.

Sodium ions also help to keep the amount of water constant in the cells of body tissues. They do this by regulating the amount of water that passes in and out of the cells. Too much water in cells could cause them to burst. Not enough water could dry out the cells or prevent chemical reactions from taking place. 

Adequate and correct (not too much, not too little)  sodium balance is necessary for transmitting nerve impulses and proper muscle function, and even a slight depletion of this concentration can cause problems. Muscles stop working. They cramp. Judgement is impaired. You fatigue and have no strength. You can become dispirited and disinclined to take encouragement or to consider. You can become ‘that’ trekker in the group.

How Much Salt per day?

So then, how much salt should we eat per day? No one seems to agree on a specific amount though everyone seems to agree there can be too much in our diet and too little can also create problems. In short, among those who care, the optimal range of sodium intake for cardiovascular health is controversial. The World Health Organisation (WHO) says we should consume less than 5g (just under a teaspoon) of salt per day.[3] To confuse things other health authorities will say things like “Adults should eat no more than 6g of salt a day (2.4g sodium) – that's around 1 teaspoon”.[4] According to the WHO most people consume too much salt—on average 9–12 grams per day, or around twice the recommended maximum level of intake.  “Most of the global population consumes between 3.0 and 6.0 g of sodium per day (7.5 to 15.0 g of salt per day).  Guidelines on cardiovascular disease prevention recommend a maximum sodium intake of 1.5 to 2.4 g per day.”[5]

Let's go with this - the National Health and Medical Research Council (NHMRC) advises Australian adults should aim to consume no more than one teaspoon (5 grams) of salt a day (or 2,000mg of sodium a day) in order to prevent chronic disease.[7] 

Does it Matter what sort of Sodium?

You may notice in various products that the sodium you take is not sodium chloride but say sodium bicarbonate (the stuff that is used to make products fizz) or in the case of products like Hydralyte two or three forms of sodium are found - sodium benzoate, sodium chloride and sodium bicarbonate. The bottom line is that it doesn't matter what form the sodium takes, you shouldn’t care more than the recommended amounts.

So What Happens When I Sweat a Lot?

There is conflicting advice here. Back to the WHO, which advises “little salt is  lost through sweat so there is no need for extra salt even on a hot and humid day, although it is important to drink a lot of water.”[11] Other authoritative sources advise that it’s when we sweat that we lose salt.[12] Importantly these studies acknowledge that everyone sweats differently and rates of sweat are not connected to BMI, environment or other factors and in the case of the studies of athletes “sweating responses could not easily be explained by hydration status, fluid intake, or training intensity. The variation in sweat response that occurred between players further emphasises the need to consider individual physiological factors when assessing an athlete’s sweat mechanics.”[13]  That message is echoed in other publications which note high sweat rates in athletes result in the loss of fluids and of sodium.

Where Can I get my daily Sodium?

A quick check of the cupboard will show you where you will find sodium – mostly in processed foods. Sodium is a natural preservative so you will find it in a lot of products. Vegemite has 3300mg per 100g though of course 100g on your toast is way too much of the black gold. But 165mg per serve is still high number. Peanut butter has 121mg per serve. The bread in the fridge at the time of writing has 265mg per 100g And so on and so on. As a general rule low salt is considered to be 120mg per 100g or less. It’s worth checking those labels when you are food planning.

When we are trekking the best source of sodium can be the freeze dried food you have thrown in the pack. My favourite Campers Panty Mango Curry Chicken has an average of 995mg of sodium per serving. That's roughly half of my daily intake and puts me in good shape with my meal planning. 

So Where Does that Leave Me?

You should know how much salt is in your trekking diet and how much you need by way of supplement if you are working hard over long periods of time. Kokoda fits that description. Research and plan. And plan a bit more.

There are various methods to increase sodium intake, such as increased use of table salt on foods, salty snacks, sports drinks, and use of salt tablets. Emphasis on replacement of fluids is also important, but care must be taken to avoid overhydration. Simple measures such as recording daily pre- and post exercise body weight can aid in making fluid and sodium ingestion decisions; in some cases, a comprehensive evaluation is necessary.”[14]

Recommendations

You do need to do your own homework and determine what works for you and what does not. Indeed, studies of athletes and their hydration and sodium gain/loss commend the very personal approach each athlete needs to take to managing their sodium balances.[15] Do you need to take salt tablets? Maybe you do. Maybe not.  Perhaps you just need to have some food that will give you that extra shot of sodium you need.  On a trek to Barrington Tops in January 2019 we experienced very high humidity over the course of a twenty kilometre route which ascended the whole way. A couple of packets of potato crisps made all the difference and proved an instant reviver in lieu of salt tablets.

 

Here is our own approach to managing sodium in our trekking food planning.

  1. First understand that our daily input of sodium should be about 2000mg. Measure intake against that level.
  2. Second, understand that you may (and are even likely to) lose sodium as you sweat, especially if you have a pack on and are working hard.
  3. Third, know what sodium you are taking up each day in your food and drink. Check those labels to ensure you are not cutting yourself short if you are working hard. 
  4. Fourth, understand the range of options for taking up salt each day. Snacks, drinks, salt tablets and adjust that sodium intake accordingly.
  5. Keep the water intake up. It's not just about sodium.

 

Other Reading

http://www.triathlon-hacks.com/salt-tablets-runners/

https://www.ahajournals.org/doi/full/10.1161/01.HYP.0000102864.05174.E8

 

 

[1] Sodium Chloride Dana M. Barry The Gale Encyclopedia of Science. Ed. K. Lee Lerner and Brenda Wilmoth Lerner. Vol. 7. 5th ed. Farmington Hills, MI: Gale, 2014. p4019-4021.

[2] Catterall, William A. 2001. A 3D view of sodium channels. Nature 409, (6823): 988-991, (accessed August 17, 2019).

[3] https://www.who.int/news-room/fact-sheets/detail/salt-reduction

[4] https://www.nhs.uk/live-well/eat-well/salt-nutrition/

[5] O'Donnell, Martin, Andrew Mente, Rangarajan Sumathy, Matthew J. McQueen, Xingyu Wang, Lisheng Liu, Yan Hou, et al. 2014. Urinary sodium and potassium excretion, mortality, and cardiovascular events. The New England journal of medicine 371, (7) (Aug 14): 612-623, 17095 (accessed August 17, 2019).

[6] https://www.nhs.uk/live-well/eat-well/salt-nutrition/

[7] https://www.betterhealth.vic.gov.au/health/healthyliving/salt

[8] O'Donnell, Martin, Andrew Mente, Rangarajan Sumathy, Matthew J. McQueen, Xingyu Wang, Lisheng Liu, Yan Hou, et al. 2014. Urinary sodium and potassium excretion, mortality, and cardiovascular events. The New England journal of medicine 371, (7) (Aug 14): 612-623, 17095 (accessed August 17, 2019).

[9] Also Torjesen, Ingrid. 2014. Too little salt in diet can be as bad as too much, study shows. BMJ (Clinical research ed.) 349, (Sep 07): 1, (accessed August 17, 2019).

[10] https://www.heartfoundation.org.au/healthy-eating/food-and-nutrition/salt/sodium-and-salt-converter

[11] https://www.who.int/news-room/fact-sheets/detail/salt-reduction

[12] Such as J.C. Gibson, L.A. Stuart-Hill, and C.A. Gaul. Hydration status and fluid and sodium balance in elite Canadian junior women’s soccer players in a cool environment, School of Exercise Science, Physical and Health Education, University of Victoria, PO Box 3015 STN CSC, Victoria, BC V8W 3P1, Canada.
W. Pethick. Canadian Sport Centre Pacific, Exercise Physiology, Victoria, BC V8P 5C2, Canada.

[13] Op.cit.

[14] “The Importance of salt in the athletes diet” Current Sports Medicine Reports August 2007, Volume 6, Issue 4, pp 237–240

[15] For example, J.C. Gibson, L.A. Stuart-Hill, and C.A. Gaul. Hydration status and fluid and sodium balance in elite Canadian junior women’s soccer players in a cool environment, School of Exercise Science, Physical and Health Education, University of Victoria, PO Box 3015 STN CSC, Victoria, BC V8W 3P1, Canada.
W. Pethick. Canadian Sport Centre Pacific, Exercise Physiology, Victoria, BC V8P 5C2, Canada.

 


Leave a comment

Please note, comments must be approved before they are published